请帮帮翻译一段长话hydrogen peroxide in sodium percar ...? also the active oxygen concentration from hydrogen peroxide in sodium percarbonate can be obtained and accurate volumetric analysis of hydrogen peroxide by reducing ceric salts to cerous salts or by l ... niuky这样理解就是一个非并列的句子了,但obtained 后面是and并非by,怎么出来的“通过……得到”的意思??查看更多